package edu.princeton.cs.algs4;
/*************************************************************************
 *  Compilation:  javac ST.java
 *  Execution:    java ST
 *  
 *  Sorted symbol table implementation using a java.util.TreeMap.
 *  Does not allow duplicates.
 *
 *  % java ST
 *
 *************************************************************************/

import java.util.SortedMap;
import java.util.TreeMap;

/**
 * This class represents an ordered symbol table. It assumes that the elements
 * are <tt>Comparable</tt>. It supports the usual <em>put</em>, <em>get</em>,
 * <em>contains</em>, and <em>remove</em> methods. It also provides ordered
 * methods for finding the <em>minimum</em>, <em>maximum</em>, <em>floor</em>,
 * and <em>ceiling</em>.
 * <p>
 * The class uses the convention that values cannot be null. Setting the value
 * associated with a key to null is equivalent to removing the key.
 * <p>
 * This implementation uses a balanced binary search tree. The <em>add</em>,
 * <em>contains</em>, <em>remove</em>, <em>minimum</em>, <em>maximum</em>,
 * <em>ceiling</em>, and <em>floor</em> methods take logarithmic time.
 * <p>
 * For additional documentation, see <a href="/algs4/45applications">Section
 * 4.5</a> of <i>Algorithms in Java, 4th Edition</i> by Robert Sedgewick and
 * Kevin Wayne.
 */
public class ST<Key extends Comparable<Key>, Value> {
	private TreeMap<Key, Value> st;

	/**
	 * Create an empty symbol table.
	 */
	public ST() {
		st = new TreeMap<Key, Value>();
	}

	/**
	 * Put key-value pair into the symbol table. Remove key from table if value
	 * is null.
	 */
	public void put(Key key, Value val) {
		if (val == null)
			st.remove(key);
		else
			st.put(key, val);
	}

	/**
	 * Return the value paired with given key; null if key is not in table.
	 */
	public Value get(Key key) {
		return st.get(key);
	}

	/**
	 * Delete the key (and paired value) from table. Return the value paired
	 * with given key; null if key is not in table.
	 */
	public Value delete(Key key) {
		return st.remove(key);
	}

	/**
	 * Is the key in the table?
	 */
	public boolean contains(Key key) {
		return st.containsKey(key);
	}

	/**
	 * How many keys are in the table?
	 */
	public int size() {
		return st.size();
	}

	/**
	 * Return an <tt>Iterable</tt> for the keys in the table. To iterate over
	 * all of the keys in the symbol table <tt>st</tt>, use the foreach
	 * notation: <tt>for (Key key : st.keys())</tt>.
	 */
	public Iterable<Key> keys() {
		return st.keySet();
	}

	/**
	 * Return the smallest key in the table.
	 */
	public Key min() {
		return st.firstKey();
	}

	/**
	 * Return the largest key in the table.
	 */
	public Key max() {
		return st.lastKey();
	}

	/**
	 * Return the smallest key in the table >= k.
	 */
	public Key ceil(Key k) {
		SortedMap<Key, Value> tail = st.tailMap(k);
		if (tail.isEmpty())
			return null;
		else
			return tail.firstKey();
	}

	/**
	 * Return the largest key in the table <= k.
	 */
	public Key floor(Key k) {
		if (st.containsKey(k))
			return k;

		// does not include key if present (!)
		SortedMap<Key, Value> head = st.headMap(k);
		if (head.isEmpty())
			return null;
		else
			return head.lastKey();
	}

	/***********************************************************************
	 * Test routine.
	 **********************************************************************/
	public static void main(String[] args) {
		ST<String, String> st = new ST<String, String>();

		// insert some key-value pairs
		st.put("www.cs.princeton.edu", "128.112.136.11");
		st.put("www.cs.princeton.edu", "128.112.136.35"); // overwrite old value
		st.put("www.princeton.edu", "128.112.130.211");
		st.put("www.math.princeton.edu", "128.112.18.11");
		st.put("www.yale.edu", "130.132.51.8");
		st.put("www.amazon.com", "207.171.163.90");
		st.put("www.simpsons.com", "209.123.16.34");
		st.put("www.stanford.edu", "171.67.16.120");
		st.put("www.google.com", "64.233.161.99");
		st.put("www.ibm.com", "129.42.16.99");
		st.put("www.apple.com", "17.254.0.91");
		st.put("www.slashdot.com", "66.35.250.150");
		st.put("www.whitehouse.gov", "204.153.49.136");
		st.put("www.espn.com", "199.181.132.250");
		st.put("www.snopes.com", "66.165.133.65");
		st.put("www.movies.com", "199.181.132.250");
		st.put("www.cnn.com", "64.236.16.20");
		st.put("www.iitb.ac.in", "202.68.145.210");

		System.out.println(st.get("www.cs.princeton.edu"));
		System.out.println(st.get("www.harvardsucks.com"));
		System.out.println(st.get("www.simpsons.com"));
		System.out.println();

		System.out.println("ceil(www.simpsonr.com) = "
				+ st.ceil("www.simpsonr.com"));
		System.out.println("ceil(www.simpsons.com) = "
				+ st.ceil("www.simpsons.com"));
		System.out.println("ceil(www.simpsont.com) = "
				+ st.ceil("www.simpsont.com"));
		System.out.println("floor(www.simpsonr.com) = "
				+ st.floor("www.simpsonr.com"));
		System.out.println("floor(www.simpsons.com) = "
				+ st.floor("www.simpsons.com"));
		System.out.println("floor(www.simpsont.com) = "
				+ st.floor("www.simpsont.com"));

		System.out.println();

		System.out.println("min key: " + st.min());
		System.out.println("max key: " + st.max());
		System.out.println("size:    " + st.size());
		System.out.println();

		// print out all key-value pairs in lexicographic order
		for (String s : st.keys())
			System.out.println(s + " " + st.get(s));
	}

}
